The invention relates to a floating bearing for a steering gear.
In most motor vehicles, there are installed power steering systems which, during steering maneuvers, generate an assisting torque and thereby reduce the steering torque that has to be imparted to the steering column by the driver.
Known power steering systems are based on a steering gear which converts the drive power of a hydraulic or electric drive and transmits said drive power to the steering column. Steering gears of said type are generally in the form of a helical rolling-type gear, and are in particular in the form of a helical wheel gear or worm gear, that is to say said steering gears comprise a gearwheel, which is connected directly or indirectly to the steering column, and a pinion which is driven by the drive via a pinion shaft.
In the case of such steering gears, gearing play has proven to be a problem, said gearing play arising owing to component tolerances, different thermal expansion of the gearing elements and wear. In particular during so-called alternating steering, that is to say during directly successive steering maneuvers with alternating steer angle, such gearing play generates undesired noises resulting from alternating abutment of opposite flanks of teeth of the pinion and gearwheel.
It is known for said gearing play to be eliminated by virtue of the pinion shaft being mounted so as to be pivotable about an axis running perpendicular to the longitudinal axis of the pinion shaft and at a distance from the toothing engagement of pinion and gearwheel, and being pressed against the gearwheel by means of one or more spring elements. Here, the pivoting capability of the pinion shaft is integrated into one of the two bearing arrangements by which the pinion shaft is mounted at its ends. Said bearing arrangement is also referred to as “fixed bearing”. The bearing arrangement in the region of the other end is then implemented with play (so-called “floating bearing”) in order to permit the deflection caused by the pivoting movement. The fixed bearing is generally provided at the drive side, whereas the floating bearing is provided on the free end of the pinion shaft. The one or more spring elements for pressing the pinion against the gearwheel are generally integrated into the floating bearing.
A (generic) floating bearing of said type, and a steering gear comprising a floating bearing of said type, are known for example from DE 10 2007 055 814 A1. In said document, the floating bearing comprises an inner ring, within which a section of a pinion shaft of the steering gear is mounted with the interposition of a rolling bearing, and an outer ring, which is held in a receptacle of a housing of the steering gear. The inner ring and outer ring form an annular gap between them. At one point on the circumference, the inner ring and the outer ring are connected via a connecting part which is in the form of a web and which is formed from an elastic material. The annular gap permits a radial movement of the inner ring and outer ring relative to one another, whereas the connecting part ensures that the inner ring and outer ring are held together, without the desired radial mobility between these being impeded.
A disadvantage of the floating bearing known from DE 10 2007 055 814 A1 is the relatively high forces required for a relative displacement of the inner ring with respect to the outer ring as a result of the deformation of the connecting part.
Taking this prior art as a starting point, the invention was based on the object of specifying an improved floating bearing for a steering gear. In particular, the improved floating bearing should be distinguished by the fact that only relatively low forces are required for the relative movement of the inner ring with respect to the outer ring.